CARLSBAD  About 10,000 runners are expected to participate in this weekend’s Carlsbad 5000, also known as the “party by the sea,” and for many people the “annual rite of spring,” event spokesman Dan Cruz said Thursday.

The weekend’s races include the Junior Carlsbad on Saturday, in which about 2,000 runners ages 12 and younger will run distances of one mile or less in 11 different events for various age groups.

The rest of the participants will run in the nine different age/gender/ability categories of Sunday’s 3.1-mile main event, the Carlsbad 5000. It begins with men age 40 and older at 7 a.m. and culminates with the professional men and women’s races a little past noon that attract what Cruz called “some of the fastest athletes on the planet.”

The races close downtown portions of Carlsbad Boulevard, Carlsbad Village Drive, Grand Avenue, and State, Roosevelt and other streets all morning Saturday and Sunday. There’s a large health expo, where food, athletic gear and other items are sold, and free samples are widely distributed.

“Spectators are always encouraged,” Cruz said. “It’s a community event that Carlsbad has become known for.”